[Version]
Fabric 1.19.3
[Mods]
Bobby
[Information]
Randomly, sections of bobby chunks simply refuse to load, with all other chunks loading.
The lack of loading for those chunks will persist through F3+A, game restarts, etc.
They will stay unloaded until you manually load the chunks by entering the server render distance.

It also happens for me, but when I set render distance to <=32, it works normally. Going 32< it starts to miss out chunk parts on complex terrains,

Render distance was 55 here.

Are you certain that a game restart doesn't fix it?
Which other mods are you using (based on your screenshots I'm guessing there's at least some type of freecam involved)? Does it happen without any third-party mods?
How often do existing chunks disappear? Is this a daily thing or a rare thing? Is there some way to reliably re-produce it? E.g. if you take a backup of the .bobby folder before entering server view distance, and then restore the backup after leaving server view distance again, do those chunks break again after a restart?
And finally, please attach the latest.log, it might contain errors that could explain why the chunks do not render.